Symmetry-Breaking Charge Transfer of Visible Light Absorbing Systems: Zinc Dipyrrins

Trinh, Cong T.; Kirlikovali, Kent O.; Das, Saptaparna; Ener, Maraia E.; Gray, Harry B.; Djurovich, Peter I.; Bradforth, Stephen E.; Thompson, Mark E.

doi:10.1021/jp506855t

Cited by 109 publications

(193 citation statements)

References 63 publications

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“…29 The authors performed transient absorption spectroscopy, thereby disclosing that 1 π-π * photoexcited homoleptic complexes undergo symmetrybreaking charge transfer to produce the charge-separated state in polar solvents. They also elucidated that in non-polar solvents such as toluene, thermal equilibrium occurs between the 1 π-π * state and the charge-separated state.…”

Section: Heteroleptic Bis and Tris(dipyrrinato)metal Complexesmentioning

confidence: 99%

New aspects in bis and tris(dipyrrinato)metal complexes: bright luminescence, self-assembled nanoarchitectures, and materials applications

et al. 2015

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Dipyrrins serve as monovalent bidentate ligand molecules that coordinate to various cations. Their BF 2 complexes, 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene and its derivatives (BODIPYs), exhibit excellent photostability, strong light absorption, and high fluorescence quantum yield, thereby encouraging their application in various fields, e.g., as biological and biomedical fluorescent markers. Dipyrrin may also accept a wide variety of metal ions spontaneously. However, dipyrrin metal complexes have been disregarded from materials science research. This review article summarizes recent progress in bis(dipyrrinato)metal(II) and tris(dipyrrinato)metal(III) complexes from the viewpoint of materials chemistry. Section 2 describes a series of efforts aimed to realize intense luminescence superior to or comparable with that of BODIPYs. The spontaneous coordination of these complexes enables them to construct self-assembled nanoarchitectures, such as supramolecules and coordination polymers that form one-dimensional nanowires, two-dimensional nanosheets, and metal-organic frameworks. Section 3 describes such alluring molecular superstructures. Section 4 discusses potential applications based on these nanoarchitectures, such as thermoelectric and photoelectric conversion. aimed to realize intense luminescence superior to or comparable with that of BODIPYs. Section 3 discusses the selfassembly of bis and tris(dipyrrinato)metal complexes, which results in the formation of alluring nanoarchitectures, such as supramolecules and coordination polymers giving rise to onedimensional nanowires, two-dimensional nanosheets, and metal-organic frameworks (MOFs) and porous coordination polymers (PCPs). Section 4 describes potential applications based on these nanoarchitectures. Pursuit of bright luminescenceA plain BODIPY shows intense absorption and bright fluorescence at approximately 500 nm, which are derived from the 1 π-π * transition of the dipyrrinato ligand. 5-16 The absorption and fluorescence may be redshifted upon the introduction of substituents on the dipyrrinato ligand, covering the region 500-900 nm. BODIPYs are good fluorophores even in polar solvents such as water. In sharp contrast, dipyrrin metal complexes have long been believed to be non-luminescent or weakly luminescent. This drawback seriously reduces the value of dipyrrinato-metal complexes in applications in which they serve, for example, as photosensitizers. In this section, the authors concentrate on efforts to improve the luminescent ability of bis and tris(bisdipyrrinato)metal complexes. For comprehensive knowledge on the whole types of luminescent dipyrrinato-metal complexes (i.e. mono(dipyrrinato)metal complexes with ancillary ligands other than dipyrrins), please see a comprehensive review article contributed by Baudron. 2

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Section: Heteroleptic Bis and Tris(dipyrrinato)metal Complexesmentioning

confidence: 99%

New aspects in bis and tris(dipyrrinato)metal complexes: bright luminescence, self-assembled nanoarchitectures, and materials applications

et al. 2015

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“…1 These systems include molecules containing two or more identical chromophores where the excited subunit can act either as electron donor (D) or acceptor (A). [2][3][4][5][6][7][8][9][10][11][12][13] Such symmetry-breaking (SB) charge separation process could be advantageously exploited for applications in photovoltaics and artificial photosynthesis. 9,14,15 Another class of compounds comprises multibranched molecules with a D(-π-A) n or A(-π-D) n (n = 2, 3) motif, that are attracting considerable interest for their promising two-photon absorption properties.…”

Section: Introductionmentioning

confidence: 99%

Modeling Infrared Spectral Dynamics upon Symmetry Breaking of a Photo-Excited Quadrupolar Dye

2020

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A significant number of quadrupolar dyes with a D-π-A-π-D or A-π-D-π-A structure, where D and A are electron donor and acceptor groups, were shown to undergo symmetry breaking (SB) upon optical excitation. During this process, the electronic excitation, originally distributed evenly over the molecule, concentrates on one D-π-A branch, and the molecule becomes dipolar. This process can be monitored by time resolved infra-red (TRIR) spectroscopy and causes significant spectral dynamics. A theoretical model of excited-state SB developed earlier (Ivanov, A. I. J. Phys. Chem. C, 2018, 122, 29165-29172) is extended to account for the temporal changes taking place in the IR spectrum upon SB. This model can reproduce the IR spectral dynamics observed in the −C ≡ C− stretching region with a D-π-A-π-D dye in two polar solvents using a single set of molecular parameters. This approach allows estimating the degree of asymmetry of the excited state in different solvents as well as its change during SB. Additionally, the relative contribution of the different mechanisms responsible for the splitting of the symmetric and antisymmetric −C ≡ C− stretching bands, which are both IR active upon SB, can be determined.

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“…1 For example, photoinduced symmetry-breaking charge separation has been observed in various multichromophoric systems containing several identical molecular units. [2][3][4][5][6][7][8][9][10][11][12] In those cases, charge separation takes place between one chromophore in the electronic excited state and another identical chromophore in the ground state. In the case of a biperylene derivative, the direction of the charge separation, i.e., electron or hole transfer, was shown to be entirely determined by the fluctuations of the surrounding solvent.…”

Section: Introductionmentioning

confidence: 99%

A simple model of solvent-induced symmetry-breaking charge transfer in excited quadrupolar molecules

Ivanov

Dereka

Vauthey

2017

The Journal of Chemical Physics

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A simple model has been developed to describe the symmetry-breaking of the electronic distribution of A-D-A type molecules in the excited state, where D is an electron donor and A and A are identical acceptors. The origin of this process is usually associated with the interaction between the molecule and the solvent polarization that stabilizes an asymmetric and dipolar state, with a larger charge transfer on one side than on the other. An additional symmetry-breaking mechanism involving the direct Coulomb interaction of the charges on the acceptors is proposed. At the same time, the electronic coupling between the two degenerate states, which correspond to the transferred charge being localised either on A or A, favours a quadrupolar excited state with equal amount of charge-transfer on both sides. Because of these counteracting effects, symmetry breaking is only feasible when the electronic coupling remains below a threshold value, which depends on the solvation energy and the Coulomb repulsion energy between the charges located on A and A. This model allows reproducing the solvent polarity dependence of the symmetry-breaking reported recently using time-resolved infrared spectroscopy.

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Symmetry-Breaking Charge Transfer of Visible Light Absorbing Systems: Zinc Dipyrrins

Cited by 109 publications

References 63 publications

New aspects in bis and tris(dipyrrinato)metal complexes: bright luminescence, self-assembled nanoarchitectures, and materials applications

New aspects in bis and tris(dipyrrinato)metal complexes: bright luminescence, self-assembled nanoarchitectures, and materials applications

Modeling Infrared Spectral Dynamics upon Symmetry Breaking of a Photo-Excited Quadrupolar Dye

A simple model of solvent-induced symmetry-breaking charge transfer in excited quadrupolar molecules

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